A current uplink power control system for satellite terminals in a satellite communication system monitors a beacon signal from a satellite. The beacon signal is held at a constant power level by the satellite. A filtered value of a long-term average downlink SINR is maintained by the satellite terminal to prevent the filtered value from changing dramatically due to continuous bad weather, such as, for example, continuous rain for a long time period. The filtered value of the long-term average of the downlink SINR is used as a clear sky indicator and is updated only when a filtered short-term average downlink SINR is less than the clear sky indicator by more than a threshold. In other words, if the filtered short-term average downlink SINR is less than the clear sky indicator by more than the threshold, then the uplink power control system would deem the satellite terminal to be experiencing downlink fade due to adverse weather conditions and the clear sky indicator would not be updated. When the filtered short-term average downlink SINR is not less than the clear sky indicator by more than a threshold, the clear sky indicator would be updated using a single time constant, which may be as long as seven or ten days.
Once the clear sky indicator has been established by the satellite terminal, if the downlink power from the satellite were to be adjusted in such a way that the new downlink SINR is greater than the clear sky indictor then the clear sky indicator would never converge to the new value. If the new SINR is less than the clear sky indicator then the clear sky indicator would converge to the new value but may take weeks (for example) during which period the terminal would perceive itself to be in a faded condition.
In a second uplink power control system, similar to the above mentioned uplink power control system, the clear sky indicator is updated using the single time constant, regardless of whether the filtered short-term average SINR is less than, greater than, or equal to the clear sky indicator.
Once the clear sky indicator has been established by the satellite terminal, if the downlink power from the satellite were to be adjusted then the clear sky indicator may take weeks (for example) to converge to the new value during which period the terminal would perceive itself to be in a faded condition.